Organic Molecules-Assisted Engineering of Ultrafine Iridium Nanoclusters with In-Situ N,O-Coordination for Efficient Hydrogen Evolution

Iridium (Ir)-based catalysts are displaying increasingly vital roles in the production of hydrogen that represents one kind of ideally clean and renewable energy substituting fossil fuels. Although great efforts have been devoted in recent years, the fabrication of Ir catalysts with adequate mass/atomic activity and stability is still a long-term goal, impeded by the aggregation of the active site and the adverse reconstruction under working conditions. To overcome these obstacles, we report an organic molecular-assisted synthetic method for ultrafine iridium nanoclusters to synthesize with in situ heteroatoms coordination (N, O, S, both N, and O) for efficient hydrogen evolution catalysis. The optimized Ir-N-O exhibits the turnover frequency (TOF) @25 mV of 7.64 s(-1) and mass activity of 5.30 A mg(-1), approximately 12 times higher than those of Ir/C. Moreover, a 16-fold enhancement compared with Ir-PC (without any heteroatom) both in TOF and mass activity can be achieved from Ir-N-O. Experimental results indicate that the ultrafine particle size and manipulated electronic state that results from N and O co-doping are beneficial to the prominent HER performance and enhanced kinetics.